USA — Visalia, California
The Big SEKI Loop is a monumental 563.3 km circumnavigation of California's Sequoia and Kings Canyon National Parks. This very challenging thru-hike ascends from ancient redwood groves into high alpine wilderness, traversing rugged ridges and dramatic canyons over 30-45 days. Expect diverse landscapes and a true test of endurance on this remote Sierra Nevada route.
Distance: 563.3 km
Elevation Gain: 21336 m
Difficulty: Very Challenging
Duration: 30-45 days
The Big SEKI Loop is a monumental undertaking that traverses the rugged heart of the Sierra Nevada, encompassing the vast wilderness of Sequoia and Kings Canyon National Parks (SEKI) in California. Spanning approximately 563.3 kilometres, this thru-hike is not merely a trail but a comprehensive circumnavigation of one of the most geologically diverse and topographically dramatic regions in North America. The route ascends from the cathedral-like groves of ancient Giant Sequoias into a high-alpine world of stark granite peaks, turquoise glacial lakes, and some of the highest mountain passes in the United States. With a staggering total elevation gain of over 21,336 metres, the Big SEKI Loop demands exceptional physical endurance, advanced navigational skills, and a deep respect for the volatile mountain environment. It is a journey that takes hikers through the Evolution Valley, across the legendary Forester Pass, and into the depths of the Kern Canyon, offering a level of solitude and immersion that few other trails on the continent can provide.
The Big SEKI Loop is often described as the "crown jewel" of California thru-hiking, a route that combines sections of the world-famous John Muir Trail (JMT) and Pacific Crest Trail (PCT) with remote, rarely visited backcountry corridors. Unlike the linear progression of the JMT, the Big SEKI Loop is a self-contained odyssey that begins and ends in the lush, forested foothills, forcing the hiker to earn every metre of elevation as they climb toward the "High Sierra." The landscape is a masterclass in glacial geology; the U-shaped valleys, hanging cirques, and polished granite domes tell a story of ice and time that spans millions of years. This is a trail of extremes: you will find yourself standing beneath the General Sherman Tree—the largest living thing on Earth—one week, and struggling for breath atop a 4,000-metre pass the next.
The loop is fundamentally defined by its verticality. The Sierra Nevada is a tilted fault block, with a gentle western slope and a precipitous eastern escarpment. The Big SEKI Loop dances along this crest, crossing numerous "cols" and passes that serve as the only gateways between isolated drainage basins. Hikers must navigate the "Big Five" passes of the southern Sierra—Mather, Pinchot, Glen, Forester, and Muir—each offering a unique perspective on the surrounding wilderness. The scale of the landscape is difficult to comprehend; the Kern Canyon alone is one of the deepest canyons in North America, a massive rift in the earth that runs straight for kilometres, flanked by the Great Western Divide and the Sierra Crest.
Solitude is a defining characteristic of this route. While sections overlapping with the JMT can be social, the vast majority of the Big SEKI Loop takes hikers into the "Deep Backcountry," where encounters with other humans are rare. Here, the rhythm of the day is dictated by the sun and the weather. Afternoon thunderstorms are a frequent summer occurrence, sending hikers scurrying off exposed ridges as lightning dances across the peaks. In the evenings, the "alpenglow" transforms the grey granite into shades of brilliant orange and pink, a phenomenon that has inspired naturalists and poets for generations. This is a journey for those who seek to test their limits against the rawest elements of the natural world.
The land encompassed by the Big SEKI Loop has been the ancestral home of Indigenous peoples for millennia. The Monache (Western Mono) lived on the western slopes, while the Owens Valley Paiute occupied the eastern side. These groups utilised the high passes—many of which the trail follows today—as trade routes, exchanging acorns and obsidian across the Sierra Crest. Evidence of their presence remains in the form of "milling stations" (bedrock mortars) and lithic scatters found in sheltered valleys. For these peoples, the mountains were not a "wilderness" to be conquered, but a vital landscape of spiritual significance and seasonal sustenance.
European exploration of the region began in earnest in the mid-19th century. The California Geological Survey, led by Josiah Whitney in the 1860s, was responsible for naming many of the prominent peaks, including Mount Whitney. However, it was the legendary naturalist John Muir who became the most vocal advocate for the preservation of these mountains. Muir’s writings about the "Range of Light" captured the imagination of the American public and were instrumental in the establishment of Sequoia National Park in 1890—the second national park in the United States—followed shortly by General Grant National Park (which later became part of Kings Canyon). Muir’s legacy is woven into the very fabric of the trail, from the Muir Hut atop Muir Pass to the eponymous John Muir Trail that forms a backbone for the loop.
The development of the trail network itself was a feat of engineering and labour. During the Great Depression, the Civilian Conservation Corps (CCC) worked tirelessly to build the stone staircases and reinforced paths that allow hikers to traverse otherwise impassable terrain. The Big SEKI Loop as a concept emerged much later, as modern thru-hikers sought to link these historic paths into a single, continuous journey. Today, the parks are managed with a focus on "Wilderness" designation, ensuring that the land remains untrammelled by man, where the natural processes of fire, flood, and regrowth continue undisturbed. Walking the Big SEKI Loop is, in many ways, a walk through the history of American conservation.
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The window for completing the Big SEKI Loop is remarkably narrow due to the extreme elevation. In a typical year, the high passes remain choked with snow until late June or early July. Attempting the loop before this time requires advanced mountaineering skills, including the use of ice axes and crampons, and the ability to navigate across featureless snowfields. Furthermore, early-season river crossings can be exceptionally dangerous, as snowmelt turns placid creeks into raging torrents capable of sweeping a hiker off their feet.
Late July to early September is the "Golden Window." During this period, the snow has mostly receded, the wildflowers are in full bloom in the alpine meadows, and the weather is generally stable. However, hikers must be prepared for the "Sierra Monsoon"—a pattern of afternoon thunderstorms that can develop rapidly. These storms bring heavy rain, hail, and dangerous lightning. The standard safety protocol is to be over the day's high pass and back below the treeline by noon. Even in mid-summer, temperatures at night can drop below freezing at higher elevations, while the valleys can experience sweltering heat exceeding 30 degrees Celsius.
Autumn (September to early October) offers crisp air, fewer mosquitoes, and the stunning yellow hues of quaking aspens. However, the days grow shorter, and the risk of a "season-ending" snowstorm increases. Once the first major winter storm hits, the high country becomes the domain of backcountry skiers and winter explorers. For the thru-hiker, the Big SEKI Loop is a race against the seasons, requiring careful timing to ensure safe passage through the most exposed sections of the High Sierra.
Stage 1: Lodgepole to Roaring River (Days 1–5)
Stage 2: Roaring River to Evolution Valley (Days 6–12)
Stage 3: Evolution Valley to Rae Lakes (Days 13–19)
Stage 4: Rae Lakes to Mount Whitney (Days 20–26)
Stage 5: Mount Whitney to Kern Canyon (Days 27–31)
Stage 6: Kern Canyon to Lodgepole (Days 32–35)
Important Notes:
Planning the Big SEKI Loop is a logistical undertaking that requires months of preparation. The primary challenge is resupply. Because the loop stays deep in the wilderness for over 500 kilometres, hikers cannot carry all their food at once. Most organisers coordinate resupply buckets to be mailed to Muir Trail Ranch (MTR) or Vermilion Valley Resort (VVR), though these require significant detours from the main loop. Alternatively, hikers can arrange for a "packer" (mule train) to drop food at specific locations, though this is expensive. Another common strategy is to hike out over Kearsarge Pass to the town of Independence for a full resupply and a "zero day" (rest day).
Physical preparation is non-negotiable. You will be carrying a heavy pack (often 15–22 kg with food and water) at altitudes consistently above 3,000 metres. Training should focus on weighted hill climbs and cardiovascular endurance. Acclimatisation is also critical; spending 2–3 nights at the trailhead elevation (approx. 2,000 m) before starting the hike can significantly reduce the risk of Acute Mountain Sickness (AMS).
The Big SEKI Loop is a wilderness thru-hike, meaning there are no huts, lodges, or permanent shelters along the route (with the exception of the historic Muir Hut, which is for emergency use only). Accommodation is strictly backcountry camping.
Camping Regulations:
Facilities:
Securing a wilderness permit for the Big SEKI Loop is a competitive process, as the parks operate under a strict quota system to protect the wilderness character of the High Sierra. Permits are required for all overnight stays in the backcountry.
The Booking Process:
Costs and Fees:
Specific Requirements: If your route includes the summit of Mount Whitney and you plan to exit via Whitney Portal (on the eastern side), you may need a specific "Whitney Zone" permit, which is managed via a separate lottery. However, if you are traversing the park and staying on the western side of the crest, a standard SEKI wilderness permit is usually sufficient. Always verify the latest boundary rules with the Wilderness Office.
Detailed route notes, maps, logistics & tips for the The Big Seki Loop (PDF).
Precisely traced GPX for the The Big Seki Loop, ready for your GPS or favourite mapping app.
The region surrounding Sequoia and Kings Canyon National Parks offers world-class attractions that are worth visiting before or after your thru-hike:
High Altitude Hazards: Much of the Big SEKI Loop stays above 3,000 metres. Acute Mountain Sickness (AMS) is a genuine risk. Symptoms include headache, nausea, and fatigue. The only cure is descent. More serious conditions like High Altitude Pulmonary Oedema (HAPO) or Cerebral Oedema (HACO) are rare but life-threatening. Hikers should monitor themselves and their partners closely.
River Crossings: In early summer (June–July), river crossings are the leading cause of accidents in the Sierra. Evolution Creek and the Kern River can be particularly treacherous. Always unbuckle your pack's hip belt before crossing, wear shoes to protect your feet, and cross at the widest, shallowest point. If a crossing looks too dangerous, wait until early morning when the flow is lower, or find a different route.
Wildlife: Black bears are common throughout the parks. They are generally not aggressive toward humans but are highly motivated by food. Using a bear canister is not just a rule; it is essential for the bear's survival, as "habituated" bears that learn to steal human food often have to be euthanised. Rattlesnakes are found at lower elevations (below 2,500 m), particularly in the Kern Canyon and near Mineral King. Watch where you step and place your hands.
Weather: Hypothermia can occur even in summer if you are caught in a cold rainstorm without proper gear. Lightning is a major threat on the high passes. If you hear thunder, descend immediately. Avoid standing near isolated trees or on wide-open ridges.
Emergency Communication: Cell phone service is non-existent in the backcountry. Carrying a Satellite Messenger (like a Garmin inReach or Zoleo) is highly recommended for sending check-in messages and summoning help in a life-threatening emergency.
Mount Whitney Summit: While the Big SEKI Loop passes near the base of Whitney, the 13-kilometre return trip to the summit (4,421 m) is the ultimate side quest. Standing on the highest point in the lower 48 states provides a perspective of the entire Sierra Nevada that is simply unmatched. The trail is well-maintained but the altitude makes every step a struggle.
The Ionian Basin: For experienced navigators, a detour into the Ionian Basin (near Muir Pass) offers a glimpse into one of the most remote and "lunar" landscapes in the park. This is a cross-country (off-trail) area filled with jagged peaks and deep blue lakes like Lake McDermand. It is a place of profound silence and stark beauty.
Darwin Bench: Located just above Evolution Valley, Darwin Bench is a series of alpine benches featuring cascading streams and views of the Evolution Peaks (Mt. Darwin, Mt. Mendel). It is often less crowded than the main JMT camps and offers some of the best photography opportunities on the loop.
Kern Hot Springs: Located deep in the Kern Canyon, these natural geothermal springs have been built into a small concrete tub right next to the river. Soaking in the hot water while watching the cold Kern River rush by is a highlight for many thru-hikers, providing much-needed relief for sore muscles.
The High Sierra is a fragile environment where the growing season is short and the soil is thin. With thousands of hikers visiting each year, the cumulative impact can be devastating if Leave No Trace (LNT) principles are not strictly followed. The Big SEKI Loop traverses "Wilderness" areas where the goal is to leave no evidence of your passage.
Core Principles for the Sierra:
